School of Environmental and Municipal Engineering, Lanzhou Jiaotong University , Lanzhou 730070, China.
College of Resources and Environmental Sciences, China Agricultural University , Beijing 100193, China.
Environ Sci Technol. 2017 Mar 21;51(6):3176-3186. doi: 10.1021/acs.est.6b04131. Epub 2017 Feb 28.
The electron transfer capacities (ETCs) of soil humic substances (HSs) are linked to the type and abundance of redox-active functional moieties in their structure. Natural temperature can affect the chemical structure of natural organic matter by regulating their oxidative transformation and degradation in soil. However, it is unclear if there is a direct correlation between ETC of soil HS and mean annual temperature. In this study, we assess the response of the electron-accepting and -donating capacities (EAC and EDC) of soil HSs to temperature by analyzing HSs extracted from soil set along glacial-interglacial cycles through loess-palaeosol sequences and along natural temperature gradients through latitude and altitude transects. We show that the EAC and EDC of soil HSs increase and decrease, respectively, with increasing temperature. Increased temperature facilitates the prevalence of oxidative degradation and transformation of HS in soils, thus potentially promoting the preferentially oxidative degradation of phenol moieties of HS or the oxidative transformation of electron-donating phenol moieties to electron-accepting quinone moieties in the HS structure. Consequently, the EAC and EDC of HSs in soil increase and decrease, respectively. The results of this study could help to understand biogeochemical processes, wherein the redox functionality of soil organic matter is involved in the context of increasing temperature.
土壤腐殖质（HS）的电子转移能力（ETC）与其结构中氧化还原活性官能团的类型和丰度有关。自然温度可以通过调节土壤中有机物质的氧化转化和降解来影响其化学结构。然而，土壤 HS 的 ETC 是否与年平均温度直接相关尚不清楚。在这项研究中，我们通过分析黄土-古土壤序列中沿冰川间冰期循环以及沿纬度和海拔剖面的自然温度梯度提取的土壤 HS，评估了 HS 的电子接受和供体能力（EAC 和 EDC）对温度的响应。结果表明，土壤 HS 的 EAC 和 EDC 分别随温度的升高而增加和减少。温度升高促进了 HS 在土壤中的氧化降解和转化的流行，从而可能促进 HS 中酚部分的优先氧化降解或电子供体酚部分向 HS 结构中电子受体醌部分的氧化转化。因此，土壤中 HS 的 EAC 和 EDC 分别增加和减少。这项研究的结果有助于理解生物地球化学过程，其中土壤有机物质的氧化还原功能在温度升高的背景下发挥作用。
